GPS tracking

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A GPS tracking unit is a device that uses the Global Positioning System to determine the precise location of a vehicle, person, or other asset to which it is attached and to record the position of the asset at regular intervals. The recorded location data can be stored within the tracking unit, or it may be transmitted to a central location data base, or internet-connected computer, using a cellular (GPRS), radio, or satellite modem embedded in the unit. This allows the asset's location to be displayed against a map backdrop either in real-time or when analysing the track later, using customized software.

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[edit] Types of GPS trackers

One type of tracker transmits the GPS coordinates through instant "text messaging", using SMS or competing standard services. GPS tracking devices can be useful for finding a lost dog, or recovering a stolen car. GPS trackers built into animal collars for various types of wildlife are useful in studying their activities and movements.

GPS trackers can be as small as a pager and can determine the vehicle's speed and location at any time, and map it automatically.

In the sport of gliding, competitors are sent to fly over closed circuit tasks of hundreds of kilometres. GPS loggers are used to prove that the competitors completed the task and stayed away from controlled airspace. The data stored over many hours in the loggers is downloaded after the flight is completed and is analysed by computing the start and finish times so determining the fastest competitors. In recent World Gliding Championships telemetry has also been used to transmit the positions of competitors. These are then displayed against three-dimensional scenery and the positions of the other competitors. Increasingly popular is FLARM which broadcasts a GPS position and velocity to other aircraft. Algorithms are then used to warn of potential collisions.

GPS Trackers or AVL (Automatic Vehicle Location) devices are an essential part of commercial fleet management solutions. In addition to tracking a vehicle's position in real-time, AVL units can be used for communications with the drivers, monitoring driving habits and fuel consumption, increasing security, reducing incidents of theft and preventing unauthorized use of equipment.

[edit] Potential abuse of GPS trackers

In the US, the use of GPS trackers by police requires a search warrant, but use by a private citizen does not, as the Fourth Amendment does not limit the actions of private citizens. These devices can also raise concerns about personal privacy. Over time, the information collected could reveal a typical pattern of movements.

[edit] Countermeasures against GPS trackers

The consumer electronics market was quick to offer remedies (radar detectors) to radar guns; a similar market may exist for devices to counter satellite tracking devices. Radio jamming of the relevant GPS or cell phone frequencies would be an option, as would a device which could detect the RF emissions of the GPS receiver circuitry. Though jamming of GPS signals could create a safety hazard to vehicles or aircraft within line of sight of the jammer and any deliberate radio interference is likely to be illegal in most western countries.

Besides this, jamming an industrial grade GPS transmitter would only work temporarily because most of them use a "store and forward" procedure to store up points that were not received and transmit them again later. This capability is built-in so tracked vehicles don't lose data when they are out of cellular range temporarily.

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